1. Field
The presently disclosed subject matter relates to a breast pump for expressing milk.
2. Description of the Related Art
Breast pumps having a horn-shaped milking portion with an enlarged diameter that is brought into contact with the breast of a mother, or in other words an enlarged-diameter milking portion, are widely used.
In a well-known constitution for ensuring that the milk, which is formed into a mist by negative pressure generated during milking, does not leak out, a recess is provided in an upper end of a breast pump main body or the like and a deformable member such as a diaphragm is housed in the recess.
More specifically, in a well-known manual breast pump disclosed in U.S. Pat. No. 5,749,850, a handle is connected to the diaphragm, and as a result of the reciprocating motion of the handle, the diaphragm is repeatedly pulled upward, thereby forming negative pressure.
Several other breast pumps having a similar constitution to the breast pump of U.S. Pat. No. 6,749,582 (WO2003/013628, WO2004/000390, and so on) are known.
In the breast pump described in U.S. Pat. No. 5,749,850, a space communicating with a passage that leads from the horn-shaped milking portion is provided in the upper portion of a container for storing liquid, and the volume of this space is varied by the diaphragm.
Hence, the space for forming the negative pressure used for milking is large, and therefore a large volume must be suctioned, leading to deterioration of the suction efficiency.
Further, since the space is formed in a location outside of the horn-shaped milking portion and the diaphragm is attached thereto, a diaphragm attachment structure is used which is complicated and difficult to dismantle. Therefore, it is difficult to clean the breast pump thoroughly, which is inconvenient in terms of hygienic use.